Electronic structure of LaIrIn5 and f-electron character in its related Ce-115 compounds

Abstract

LaIrIn$_5$ is a reference compound of the heavy-fermion superconductor CeIrIn$_5$.The lack of f electrons in LaIrIn$_5$ indicates that there should not be any f electron participatingin the construction of its Fermi surface. Thus the electronic structure comparison between LaIrIn$_5$and CeIrIn$_5$ provides a good platform to study the properties of f electrons. Here angle-resolvedphotoemission spectroscopy (ARPES) measurements and density functional theory (DFT)calculations are performed to study the electronic structures of LaIrIn$_5$ and CeIrIn$_5$.We find the valence band structures of the two materials are similar to each other, exceptfor the absence of f bands in LaIrIn$_5$. By analyzing the Fermi crossings of the threeconduction bands of the two materials quantitatively, we find the volumes of the electronpockets $\\upalpha$ and $\\upbeta$ around the M$'$ point become larger from LaIrIn$_5$ to CeIrIn$_5$,while the hole pocket $\\upgamma$ around the $\\Gamma'$ point becomes smaller. Together with thecalculation results, we confirm that this is mainly originated from the f-electron contribution,while the lattice-constant difference between LaIrIn$_5$ and CeIrIn$_5$only has a finite influence.We also give a summary of the f-electron character in its related Ce-115 heavy fermion compounds. Our results may be essential for the complete microscopic understandingof the 115 compounds and the related heavy-fermion systems.